Multistage compressor



April 1945- H. R. RICARDO 2,373,730

MULTISTAGE COMPRESSOR Filed Sept. 16. 1942 4 Sheets-Sheet 1 April 17,1945.

H. R. RICARDO MULTISTAGE COMPRESSOR Filed Sept. 16," 1942 4 Sheets-Sheet2 'f fi Aim] 1945' H. R. RICARDO MULTIS'I'AGE COMPRESSOR Filed Sept. 16,1942 4 Sheets-Sheet 3 5% ATTORNEY April 17, 1945. H. R. RICARDO R2,373,780

MULTISTAGE COMPRESSOR Filed Sept. 16, 1942 4 Sheets-Sheet 4 PatentedApr. 17, 1945 UNITED fSTATE 1 MULTISTAGE COMPRESSOR Harry Ralph Ricardo,London, England A Application September 16, 1942','Serial No.458,54$

.In Great Britain September 29, 1941 sol-aims." (01. 230484) Thisinvention relates to a multi-stage compress'orof the reciprocatingtypec'ombined with and driven by an'internal combustionengineand v hasforits objectto provide a compact and efficient construction. a

According to this invention a crankshaft which is driven directly athigh speed by the engine is "combined with a second crankshaft which isdriven from the high speed crankshaft at half its speed, and-means areprovided whereby the first stage of the compressor is directly operatedby the first crankshaft while the valves of thi stage are operated bythe second crankshaft which also operates the second and subsequentstages of the compressor. The engine operates on the fourstroke cycle.The first crankshaft has two cranks at 360 and between them one crank at180, the two cranks at 360 being actedjon by the pistons in the twocylinders of the engine while the intermediate crank at 180 operates thepiston'of the first stage of the compressor. Thesecond crankshaft orIayshaft which is drivenby gearing from the first crankshaft operatespiston valves which function for the first stage and also the piston ofthe subsequent stages. With such an arrangement' the first stagecompression serves on the one hand to balance partially the torquereaction and on the other hand to complete the primary balance bf'theengine crankshaft.

In this construction as a result of the employmentof the two crankshaftsgeared together to rotate at different speeds each piston in'the firststage'is reciprocated in its cylinderat a higher. speed than the pistonsin the cylinders of the subsequent stages.

It is to beunderstood' that While in the arrangement described above,only "a single cylinder is indicated a being comprised in the firststage, there may be two or more cylinders in that stage with'acorresponding numberof cylinders in the higher stages. However, aconstruction in which there are two engine cylinders operating on theone high speed crankshaft which drives the first stage of. thecompressor, and: two or three further stages operated by theseconducrankshaft inthe manner indicated, constitutes a convenient andcompact unit. Multiples of this unit may becombined and coupledtogether, or a's milar, but larger ders together with the pistons of thehigher stagesbeing all driven from a second crankshaft driven at halfspeed from the first crankshaft.

; The accompanying drawingasome of which are diagrammatic, illustrate byway of example a con struction which may be used in carrying'theinventioninto practice. In these drawings:

Figure 1,"which is divided, is'a sectional elevati'on in a verticalplane which includes the axis of the main crankshaft and the axes of thetwo cylinders of the engine and of the cylinder of'the first stage ofthe compressor which is disposed between the engine cylinders.

Figure 2 is a diagrammatic plan'of the engine and compressor:

v Figure 3 is a part-sectional elevation on the line 3- -3 in Figure 2and looking in-the direction of the arrows. v

* Figure 4 is a diagrammatic transverse section on'th'e' line 4-' i 'inFigure 3 the section passing through one of the cylinders of'the engine;

Figure 5 is 'asimilar transverse section on the broken 1ine5'-5 inFigure 2;

',Figure Sis a similar view the section being i taken on the broken lineB6 in Figure 2. 25

Referring to Figure 1 the main or engine crankshaft A is three throwwith the angular positions of the two cranksA and A of the powercylinders'similar, thatis at 360 and the intermediate crank A at 180with respect to the cranks A and A2, the crank A actuating the piston ofthe first stage of the compressor. The two cranks A and. A are acted onrespectively by the two pistons B and C in the power cylinders B and Cwhile between these cylinders lies the cylinder D of the first stage ofthe compressor with the piston D therein which is coupled to theintermediate crank A 'B'earings E arelprovided for the cranks A A and AAt one end of the crankshaft is mounted at F- a centrifugal governor andonthe other end is' a gear wheel G which meshes with a gear wheel G onthe second crankshaft H which is thus driven fromthe main shaft A and athalf the speed of the main shaft. It is convenient, as shown in Figures4, 5 and 6, to place the second crankshaft H with its axis in ahorizontal plane which lies above the horizontal plane in which lies theaxi of the main crankshaft A. The crankshaft H is provided with twocranks H and H and it also carries the cams J by which are operated,through push rods J the inlet and exv hau'st valves of the powercylinders B and C The two engine cylinders B and C are of normal typeand construction, the engine operatin on the four-stroke cycl'elandeither with spark ignition or compression ignition. Poppet valves K, Kare provided and it is convenient to arrange means whereby the exhaustvalves K may be held off their seats on occasion. This may be effectedby a cam L which when a hand lever L is moved will act on the end of thevalve spindle K the cams operative on the two exhaust valves beingcoupled through a link L so that they will be brought into actiontogether. To facilitate starting, the cylinder D of the first stage isprovided with a poppet valve M controlling a port in the head of thecylinder, the valve being normally kept on its seat by spring action,but by moving a hand lever M a cam M is caused to pres on the end of thevalve spindle and thus lift the valve off its seat, in this waypreventing the compression of gas drawn into the cylinder as thecrankshaft A is rotated.

As seen in plan in Figure 2 the cylinder D of the first stage appearsbetween the two power cylinders "5 C of the engine with the valves N, Oof the first stage in their cylinders N 0 and the cylinders P, Q and Rof the higher stages towards One side of the first stage cylinder D. Asmentioned these valves N, 0 are piston valves and they are arrangedcoaxial with the pistons P Q of the higher stages to which these valvesare coupled by rods S, T each of which extends between the piston of thehigher stage and a partition within the piston valve which is formedhollow. Conveniently the suction valve N is thus connected to the pistonP of the second stage, while the delivery valve 0 of the first stage isconnected to th piston Q of the third stage. The piston R of the fourthstage is constituted by a plunger-like projection from the upper side ofthe piston P of the second stage. The valves of the cylinders of thesecond, third and fourth stages are of a type which operatesautomatically.

An intercooler is preferably provided and arranged so that the air fromthe first stage passes through it before entering the cylinder of thesecond stage, and intercoolers may be employed between other stages andan aftercooler may be provided after the highest stage.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a multi-stage compressor of the reciprocating type the combinationof an internal combustion engine with a crankshaft driven thereby, atleast one cylinder with piston'therein constituting the first stage ofthe compressor which is directly operated by the engine crankshaft, asecond crankshaft with means whereby it is driven from the enginecrankshaft at half the speed of the latter, inlet and delivery valvesfor this first stage with means by which these valves are actuated bythe said second crankshaft, at least one cylinder with piston thereinconstituting a subseouent stage of the compressor and means whereby anysuch subsequent stage is onerated by the said second crankshaft, andvalves for the said internal combustion engine with means whereby theyare actuated by the said second crankshaft.

2. In a multi-stage compressor of the reciprocating type the combinationof an internal combustion engine having at least two cylinders andoperating on the four-stroke cycle. a crankshaft having at least twocranks at 360 with one crank between them at 180 the two cranks at 360being acted on by the internal combustion engine, at least one cylinderwith piston therein constituting the first stage of the compressor andoperated by the said crank at 180 between the said engine crankshaft athalf the speed of the latter, inlet and delivery valves for the firststage of the compressor with means by which these valves are actuated bythe said second crankshaft, at least one cylinder with piston thereinconstituting a subsequent stage of the compressor and means by which anysuch subsequent stage is operated by the said second crankshaft, andvalves for the said internal combustion engine with means whereby theyare actuated by the said second crankshaft.

3. In a multi-stage compressor of the reciprocating type the combinationof an internal combustion engine with a crankshaft driven thereby, atleast one cylinder with piston therein constituting the first stage ofthe compressor which is directly operated by the engine crankshaft, asecond crankshaft with means whereby it is driven from the enginecrankshaft at half the speed of the latter, at least two cylinders withpistons therein constituting subsequent stages of the compressor andoperated by separate cranks on the said second crankshaft, inlet anddelivery valves for the said first stage with means whereby these valvesare actuated by the said second' crankshaft, and valves for the saidinternal combustion engine withmea-ns whereby they are actuated by thesaid second crankshaft.

4. In a multi-stage compressor of the reciprocating type the combinationof an internal combustion engine with a crankshaft driven thereby, atleast one cylinder with'piston therein constituting the first stage ofthe compressor which is directly operated by the engine crankshaft, asecond crankshaft with means by which it is driven from the enginecrankshaft at half the speed of the latter, at least two cylinders withpistons therein constituting subsequent stages of the compressor andoperated by separate cranks on the said second crankshaft, inlet anddelivery valves for the said first stage these valves being pistonvalves which are coaxial with and connected to the pistons in the saidcylinders of the subsequent stages and thus are actuated by the saidsecond crankshaft, and valves for the said internal combustion enginewith means whereby they are actuated by the said second crankshaft.

5. In a multi-stage compressor of the reciproeating type the combinationof an internal combustion engine having at least two cylinders andoperating on the four-stroke cycle, a crankshaft having at least twocranks at 360 with one crank between them at 180 the two cranks at 360being acted on by the internal combustion engine, at least one cylinderwith piston therein constituting the first stage of the compressor andoperated by the said crank at 180 between the cranks on the crankshaftwhich are acted on by the internal combustion engine, a secondcrankshaft with means by which it is driven from the said enginecrankshaft at half the speed of the latter, at least two cylinders withpistons therein constituting subsequent stages of the compressor andoperated by separate cranks on the said second crankshaft, inlet anddelivery valves for the first stage these valves being piston valveswhich are coaxial with. and connected to the pistons in the saidcylinders of the subsequent stages and thus actuated by the said secondcrankshaft, and valves for the said internal combustion engine withmeans by which they are actuated by the said second crankshaft.

engine crankshaft at half the speed. of the latter, I at least twocylinders with pistons therein concranks on the crankshaft which areacted on by the internal combustion engine, a second crankshaft with twocranks at 180 and gearing by which this crankshaft is driven from the.said

stituting subsequent stages of the compressor, piston valves whichfunction as inlet and delivery valves for the first stage these valvesbeing connected to and acting as crossheads for the said pistons in thecylinders of the subsequent stages and being actuatedby the cranks onthe said second crankshaft, and valves for the said internal combustionengine with means by which they are actuated by the said. secondcrankshaft.

' HARRY RALPH RICARDO.

